WASHINGTON – The State Department’s announcement that it will expel 15 Cuban diplomats “is not a punishment” and does not signal a shift in U.S. diplomatic relations with the country, State Department Spokseperson Heather Nauert said Tuesday.

The expulsion comes in response to many members of the U.S. embassy staff in Havana being afflicted with mysterious illnesses requiring the embassy to be reduced to a skeletal emergency crew.

“The decision was made due to Cuba’s failure to take appropriate steps to protect our diplomats in accordance with its obligations under the Vienna Convention,” Secretary of State Rex Tillerson said in a news release Tuesday morning. “This order will ensure equity in our respective diplomatic operations.”

The Vienna Convention is a 1961 United Nations treaty that provides a blueprint of conditions for diplomatic relations between countries.

“We are not assigning any blame,” said Nauert at an afternoon news conference. “We don’t know who or what is causing this.”

Nauert said that U.S. personnel have been “harmed” in their ability to do their jobs in Cuba, and the expulsions will limit Cuba’s ability to conduct its operations in Washington as well.

Nauert also announced that the number of U.S. personnel in Cuba injured by the unknown attacks has risen to 22. In a Sept. 29 statement, Tillerson described the injuries as “a range of physical symptoms, including ear complaints, hearing loss, dizziness, headache, fatigue, cognitive issues, and difficulty sleeping.” 

Nauert declined to respond to questions about what actions the State Department has taken to make conditions in Cuba safer since the discovery of the attacks.

“The trouble with that is we don’t know what is causing this. We don’t know who or what is responsible,” said Nauert.

The FBI is conducting an investigation into the injuries and attacks against U.S. personnel in Cuba.